Process for the extraction of valuable ingredients from heat sensitive raw materials



Sept. 20, 1932. M. B. HOPKINS 1,877,875

PROCESS FOR THE EXTRACTION OF VALUABLE GREDIENTS FROI HEAT SENSITIVE RAWMATER'IA Filed July 29, 1929 I MAYHQN B.HOPK\N3 INVENTOR ATTORN EYPatented Sept .20, 1 932 vum'rao STATES PATENT orrlcr.

MARION E. HOPKINS, E ELIZABETH, NEW JERSEY, ASSIGNOB To STANDARD OIL DE-VELOPMENT COMPANY, A CORPORATION OF DELAWARE "rnocEss Eon THE EXTRACTIONor VALUAIBLE INGREDIENTS rEom: HEAT SENSITWE RAW MATERIALS Applicationfiled. July 29,

' The present invention relates to the art of obtaining concentratedextracts of materials sensitive to only slightl elevated temperatures,and more specifical y comprises an imcentrated extracts of pyrethrumflowers in kerosene, or other oils, and also to an improved apparatusfor accomplishing this result. The invention will be fully understoodfrom the following description and the drawing which illustrates oneform of apparatus for carrying out the process. I

The drawing is a semi-diagrammatic view in sectional elevation of anapparatus constructed according to my invention and indicates the flowof material. I

Referring to the drawing, reference numerals l, 2 and 3, indicateextraction chambers which are filled with the material to be 29extracted and which are to be used alternately, as will be described.The extract- .ing medium, a light hydrocarbon, such as butane, pentaneor hexane, or a mixture of such hydrocarbons as petroleum ether, is

forced by pump 4 from source, not shown,

through a feed line 5 and into any one of the extraction chambers byvalved branch lines 7, 8 or 9, respectively. The extracting mediumflowing through the material to be ex tracted on coming in contact withthat ma terial, dissolves the soluble ingredients. The liquid cntainingthe dissolved ingredients is removed from the base of the chambers byvalved lines 10, 11 or 12, respectively, to a manifold 13 which conductsthe liquid to a still 14, preferably by way of tower 15 mounted on thestill. The still which is used to vaporize the extracting medium fromthe extracted material and to dissolve the extracted material in anotheroil, such as kerosene is heated by a steam coil 16, or by other suitablemeans, and a regulated stream of kerosene, or other oil, with a boilingpoint higher than the extraction medium may be fed by line 17. Still 14is maintained at a temperature above the vaporization temperature of thelighter oil sothat the lighter oil 1929. Serial No. 382,009.

movable heads, not shown in detail, for' charging and discharging, andvalved branch pipes 20, 21- and 22, respectively, from a line 23,through which heated inert gas, such as nitrogen, carbon dioxide orsteam may be forced to vaporize the light oil clinging to the spentrawmaterial. The gas and vapor leave by valved vapor lines 24, 25 and 26 toa manifold 27 and cooler 28. Condensate can be removed from drum 29 andthe'remaining vapor compressed for recovery of light oil by compresser30, cooled by cooler 31- and collected in drum 32. The extracting mediumsuch as butane, hexaneor petroleum ether, after dissolving the solubleingredients of the material in chambers 1, 2 or 3, carries them to still14 where the solvent or extracting medium is va orized and precipitatesthe soluble ingre i'ents in that still. The vapors are condensed incondenser 19 and are ready for use in another or the same extraction.The extracting medium by this process can be circulated until no moresoluble ingredients are present in the material.

The extracted material, which in the case of the extraction of pyrethrumflowers is readily liquefied by heat at 5060 C. may be with-.

drawn from still 14 substantially free of light oil as the light oil isvaporized in still 14 and may be allowed to cool and harden, or it maybe withdrawn in solution in light oil, or kerosene, or heavier oildepending upon what oil is used in still '14, but in any case it isdesir able to conduct it by means of pipe 33 through pressure reductionvalve .34 into a stripping still that may be in the form of a tower 35,heated by coil 36. -Light oil vapor is removed to condenser 37, trap 38and vacuum pump 39, if it is desired to hold the tower under reducedpressure. Light oil is condensed in cooler 40 and collected in drum 41.This oil, along with that from drum 32 is taken to storage and by meansof pump 4 may pyrethrum extract is. removed from still 35 by line 42substantially free of light oil and is collected in storage (not shown).7

In the operation of the present process it has often been founddesirable to extract at temperatures below a certain point above whichthe valuable extractives are eithertotally destroyed or deteriorated.With pyrethrum the temperature should not rise above about 100 C. Thethree or more extraction chambers are alternately charged, extracted anddischarged, so that the equipment, other than the chambers may becontinuously in use.

The apparatus comprising the cycle of still 14, condenser 19 and theextraction chamber in use, is preferably maintained under pressure whichmay vary with the volatility of the solvent, but it should be aboveatmos pheric pressure and may be as high as 200 or even 500 pounds persquare inch, andso as to allow condensation at ordinary cooling watertemperature. As stated above, the temperature of still 14 should notrise above about 100 C. and this may be conveniently regulated bycontrolling pressure in the coil 1 The material to be extracted ischarged to the extraction chambers 1, 2 and 3 in a finely ground orunground condition, which latter is preferable with pyrethrum flowers,and it is preferable to use to 1 gallon of light oil per pound offlowers to be extracted. When the flowers are totally extracted, ortheir valuable eontents is reduced to the economic limit for extraction,the chamber is cut out of the cycle by operation of suitable valves,after the chamber has been allowed to drain, and another chambercontaining fresh flowers is substituted in the system. The spent chamberis then blown with hot inert gas or steam to drive the volatile solventfrom the spent flowers and the vapors are condensed so that therecovered solvent may be reused and the flowers may be dischargedwithoutfire hazard. The chamber is then dumped, recharged, and in itsturn is replaced in the extraction cycle.

When starting operations the still is filled with kerosene or other oil,which is to be used as the carrier for the extract, or with light oil ifthe extracted material is to be obtained free of solvent and heat isadded to vaporize light oil and cause its circulation as disclosed. Whenthe concentration in the kerosene is raised to the point desired, freshkerosene may be added in regulated quantity by line 17, eitherintermittently or continuously, and oil may be withdrawn from still 14and discharged with reduction of pressure into still 35 in which tracesof low boiling so vent are removed, either under the influence of vacuumor steam, or their joint action, the unvaporized oil extract may bewithdrawn from still 35, cooled and stored for use. The extractionmedium added by line 4 is to make up losses and may be added eithercontinuously or preferably at intervals and the oil from drums 32 and 41may be reused, if desired.

The quantity of kerosene added may vary over wide limits, generally.less than 1 gallon per pound of flowers used and depends only on thedesired strength of the concentrate, which may be thinned to any degreeby addition of other oil, as will be understood. When applied to theextract of pyrethrum flowers, it is preferable to use a kerosene with aninitial boiling point not below about 200 C. and end point not overabout 280 C. as indicated by the ordinary analytical distillation. Theextraction medium may be a mixture of light hydrocarbons such aspetroleum ether, or a pure hydrocarbon such as hexane, pentane, butaneor propane. It is preferable to use a mixture with an end point of notover about C. and not containing substantial quantities of hydrocarbonsboiling below propane. Such an extraction medium is particularlyadvantageous for extraction of pyrethrum flowers, since it is cap ableof removing the active insecticidal in,- gredients with a smallerproportion of inactive, darkly colored constituents than is possiblewith higher boiling solvent, such as kerosene or heavy naphtha.

It will be understood that when the extracted material is readilyliquefiable by heat, such as the material extracted from pyrethrumflowers, kerosene or heavier oil need not be added to still 14, and theextracted material may be obtained as a soft resinous substance,substantially free of hydrocarbon oil. The substance, when melted, isnot viscous or sticky and runs through the tower and pipes with ease.

The present invention,.while particularly adapted to the extractiofi ofpyrethrum flowers, is not limited to that alone, as it may be used toextract any materials ,soluble in a hydrocarbon solvent, nor is itlimited to any particular illustrative example of the apparatus or itsoperation. The invention is to be limited only to the following claimsin which it is desired to claim all novelty inherent in the invention.

I claim:

1. Method of extracting insecticidal matter from pyrethrum flowers andthe like, comprising the use of two solvents having different boilingpoints, first extracting the flowers under superatmospheric pressurewith a lower boiling hydrocarbon solvent boiling below about 70 G.,whereby insecticidal matter is dissolved, passing the resulting solutioninto a distillation zone in which the solution is mixed with a higherboiling solvent for the insecticidal matter, vaporizing the lowerboiling solvent at a temperature below about 100 C, and withdrawing theremaining solution of insecticidal matter in the heavier solvent.

2. Method according to claim 1, in which the heavier solvent is an oilof the kerosene type and the solution of insecticidal matter in theheavier solvent has an initial boiling point above about 200 C.

3. Process of extracting organic material containing ingredients solublein an aliphatic m hydrocarbon solvent and sensitive to only slightlyelevated temperatures, comprising the extraction of the material with alow boiling aliphatic hydrocarbon solvent, commingling the solutlonthus'obtained with a higher boiling aliphatic hydrocarbon solventadapted to dissolve the extracted compounds,

and removing the low boiling solvent.

MARION B. HOPKINS.

